Brush electrode

ABSTRACT

A brush electrode includes an electrode base that is connectable to an external device that is configured to generate an electrical signal or receive an electrical signal. A plurality of strand electrodes extend outward from the electrode base. A distal end of each strand electrode is configured to contact a skin surface. The strand electrodes are configured to hold an electrolyte to facilitate ionic conduction of the electrical signal to or from the skin surface.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation application of U.S. patentapplication Ser. No. 16/469,207, filed Jun. 16, 2019, which is nationalphase application of PCT/IL2017/050934, filed Aug. 22, 2017, claimingbenefit from U.S. Provisional Patent Application No. 62/434,954, filedDec. 15, 2016, all of which are incorporated herein by reference intheir entirety.

FIELD OF THE INVENTION

The present invention relates to electrodes for contact with a body.More particularly, the present invention relates to a brush electrode.

BACKGROUND OF THE INVENTION

Various medical applications or other applications benefit fromelectrodes that are noninvasive and sensitive to various electricalsignals that are produced by the body of a human, animal, other form ofliving being. For example, various noninvasive medical diagnostic,therapeutic, or research procedures may utilize such electrodes that areplaced on the skin. Such procedures include, for example,electroencephalography (EEG), electrocardiography (ECG),electromyography (EMG) and other diagnostic techniques. A diagnostic ortherapeutic technique may include electrical brain stimulation, musclestimulation, neuronal stimulation, or other types of stimulation.

In some cases, such electrodes may be utilized in a gaming system, inlie detection, in monitoring of a vehicle or machine operator, or invarious other situations, in or out of the laboratory.

Typically, an electrode for conducting electrical signals between theskin and an external device is placed or pressed onto the skin at one ormore appropriate locations (e.g., near an organ or tissue that producesan electrical signal or that is affected by an externally appliedelectrical signal). Typically, the interface between the skin and theelectrode is not an efficient conductor of electrical signals. Amongother reasons, an electronic component operates via conduction ofelectrical charges in the form of electrons and holes, while electricalsignals in physiological organs, tissues, and cells are typicallyinvolve movement of electrical charges in the form of positive andnegative ions. Conduction of an electrical signal into the body mayrequire a charge conversion by an electrochemical process.

In order to facilitate electrical conduction at the interface betweenthe skin and the electrode, a conductive medium is placed at theinterface. For example, the conductive medium may include salinesolution (e.g., permeating a sponge or other absorbent material), aconductive gel, or another wet medium. The conductive medium may beplaced onto the skin, onto the electrode, or both. For example, somedisposable electrodes are pre-embedded in a pad that may include aconductive medium, an adhesive, or both.

SUMMARY OF THE INVENTION

There is thus provided, in accordance with an embodiment of the presentinvention, a brush electrode including: an electrode base that isconnectable to an external device that is configured to generate anelectrical signal or receive an electrical signal; and a plurality ofstrand electrodes that extend outward from the electrode base, a distalend of each strand electrode configured to contact a skin surface, theplurality of strand electrodes configured to hold an electrolyte tofacilitate ionic conduction of the electrical signal to or from the skinsurface.

Furthermore, in accordance with an embodiment of the present invention,the strand electrodes are clustered into a plurality of clusters ofstrand electrodes, neighboring clusters of the plurality of clustersbeing separated from one another by gaps without any strand electrodes.

Furthermore, in accordance with an embodiment of the present invention,a cluster of the plurality of clusters is held to the base by a stapleor a ferrule.

Furthermore, in accordance with an embodiment of the present invention,the plurality of clusters are electrically connected to a singleexternal connector for connecting to the external device.

Furthermore, in accordance with an embodiment of the present invention,at least two clusters of the plurality of clusters are connected todifferent external connectors for connecting separately to the externaldevice.

Furthermore, in accordance with an embodiment of the present invention,the brush electrode includes an isolating barrier for electorallyisolating two clusters of the plurality of clusters from one another.

Furthermore, in accordance with an embodiment of the present invention,a distal face of the electrode base includes a plurality of openings,each opening configured to enable the strand electrodes of each clusterof the plurality of clusters to extend distally outward.

Furthermore, in accordance with an embodiment of the present invention,the plurality of openings are arranged in a rectangular array.

Furthermore, in accordance with an embodiment of the present invention,the plurality of strand electrodes are configured to hold theelectrolyte by capillary forces.

Furthermore, in accordance with an embodiment of the present invention,a strand electrode of the plurality of strand electrodes includes ahollow core that is configured to be filled with the electrolyte, or isconfigured to absorb or adsorb the electrolyte.

Furthermore, in accordance with an embodiment of the present invention,a strand electrode of the plurality of strand electrodes is electricallyresistive or ionically conducting.

Furthermore, in accordance with an embodiment of the present invention,a proximal segment of a strand electrode of the plurality of strandelectrodes is electronically conducting, and a distal segment of thatstrand electrode is electrically resistive or ionically conducting.

Furthermore, in accordance with an embodiment of the present invention,the brush electrode includes an electrolyte reservoir.

Furthermore, in accordance with an embodiment of the present invention,the plurality of strand electrodes includes strand electrodes ofdifferent lengths.

Furthermore, in accordance with an embodiment of the present invention,the electrode base is curved.

Furthermore, in accordance with an embodiment of the present invention,the strand electrodes extend substantially perpendicularly outward fromthe electrode base.

Furthermore, in accordance with an embodiment of the present invention,the strand electrodes extend outward from the electrode base at anoblique angle to the electrode base.

Furthermore, in accordance with an embodiment of the present invention,the strand electrodes are tilted laterally outward.

Furthermore, in accordance with an embodiment of the present invention,a plurality of neighboring strand electrodes of the plurality of strandelectrodes terminate in a single ion-conducting tip.

Furthermore, in accordance with an embodiment of the present invention,a plurality of strand electrodes are fully or partially covered by asleeve.

BRIEF DESCRIPTION OF THE DRAWINGS

In order for the present invention, to be better understood and for itspractical applications to be appreciated, the following Figures areprovided and referenced hereafter. It should be noted that the Figuresare given as examples only and in no way limit the scope of theinvention. Like components are denoted by like reference numerals.

FIG. 1 schematically illustrates a cross section of a brush electrode,in accordance with an embodiment of the present invention.

FIG. 2 schematically illustrates a cross section of a brush electrodehaving strand electrodes arranged in clusters in the form of tufts heldin place by staples.

FIG. 3 schematically illustrates a cross section of a brush electrodehaving clusters of strand electrodes that are held in place by ferrules.

FIG. 4 schematically illustrates a cross section of a brush electrode asshown in FIG. 3 , with an electrolyte solution adhering to the clustersof conductive strand electrodes.

FIG. 5A schematically illustrates a variant of a cross section of abrush electrode as shown in FIG. 4 , with segmented strand electrodesthat are partially electrically conductive and partially nonconductive.

FIG. 5B schematically illustrates a segmented strand electrode of thebrush electrode shown in FIG. 5A.

FIG. 6 schematically illustrates a variant of a cross section of a brushelectrode as shown in FIG. 4 , where each electrode cluster includesdifferent types of strand electrodes.

FIG. 7 schematically illustrates a variant of a cross section of a brushelectrode as shown in FIG. 4 , where electrolysis is configured to occurat a proximal end of each strand electrode.

FIG. 8 schematically illustrates an example of a cross section of abrush electrode that includes an electrolyte reservoir within theelectrode casing.

FIG. 9 schematically illustrates a variant of the cross section of abrush electrode shown in FIG. 3 , with strand electrodes havingdifferent lengths.

FIG. 10 schematically illustrates a variant of the cross section of abrush electrode shown in FIG. 3 , having a curved electrode base.

FIG. 11 schematically illustrates a variant of the cross section of abrush electrode shown in FIG. 3 , having tilted strand electrodes.

FIG. 12 schematically illustrates a variant of the cross section of abrush electrode shown in FIG. 11 , having strand electrodes that aretilted laterally outward.

FIG. 13 schematically illustrates a variant of the cross section of abrush electrode shown in FIG. 3 , configured to separately connect eachelectrode cluster to an external device.

FIG. 14 schematically illustrates a variant of the cross section of abrush electrode shown in FIG. 3 , with isolating barriers.

FIG. 15 schematically illustrates a variant of the cross section of abrush electrode shown in FIG. 13 , having isolating barriers betweenelectrode clusters.

FIG. 16 schematically illustrates a variant of the cross section of abrush electrode shown in FIG. 3 , where the distal ends of groups ofstrand electrodes within a single electrode cluster terminate in anion-conducting tip.

FIG. 17 schematically a variant of the cross section of a brushelectrode shown in FIG. 3 , where all strand electrodes in an electrodecluster terminate in a single ion-conducting tip.

FIG. 18 schematically illustrates variants of electrode clusters of thecross section of a brush electrode shown in FIG. 17 .

FIG. 19 schematically illustrates variants in the forms of longitudinalcross sections strand electrodes for a brush electrode as shown in FIG.1 .

FIG. 20 schematically illustrates variants of a transversecross-sectional shape of a strand electrode for a brush electrode asshown in FIG. 1 .

FIG. 21 schematically illustrates a face of an electrode base of a brushelectrode as shown in cross section in FIG. 3 .

FIG. 22 schematically illustrates a system that includes a plurality ofbrush electrodes, in accordance with an embodiment of the presentinvention.

FIG. 23 schematically illustrates a brush electrode with hollow strandelectrodes, in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In the following detailed description, numerous specific details are setforth in order to provide a thorough understanding of the invention.However, it will be understood by those of ordinary skill in the artthat the invention may be practiced without these specific details. Inother instances, well-known methods, procedures, components, modules,units and/or circuits have not been described in detail so as not toobscure the invention.

Although embodiments of the invention are not limited in this regard,discussions utilizing terms such as, for example, “processing,”“computing,” “calculating,” “determining,” “establishing”, “analyzing”,“checking”, or the like, may refer to operation(s) and/or process(es) ofa computer, a computing platform, a computing system, or otherelectronic computing device, that manipulates and/or transforms datarepresented as physical (e.g., electronic) quantities within thecomputer's registers and/or memories into other data similarlyrepresented as physical quantities within the computer's registersand/or memories or other information non-transitory storage medium(e.g., a memory) that may store instructions to perform operationsand/or processes. Although embodiments of the invention are not limitedin this regard, the terms “plurality” and “a plurality” as used hereinmay include, for example, “multiple” or “two or more”. The terms“plurality” or “a plurality” may be used throughout the specification todescribe two or more components, devices, elements, units, parameters,or the like. Unless explicitly stated, the method embodiments describedherein are not constrained to a particular order or sequence.Additionally, some of the described method embodiments or elementsthereof can occur or be performed simultaneously, at the same point intime, or concurrently. Unless otherwise indicated, the conjunction “or”as used herein is to be understood as inclusive (any or all of thestated options).

In accordance with an embodiment of the present invention, an electrodefor detecting via skin an electrical signal that is generated by a body(e.g., human, animal, or other living body), or for applying anelectrical signal to the body via the skin, is in the form of strandelectrodes (having a form suggestive of bristles of a brush). Anelectrode that includes such strand electrodes is referred to herein asa brush electrode.

A distal end of a strand electrode is configured to be placed against askin surface of the body and to enable conduction of an electricalsignal between the body and an external device. For example, physicalproperties of the strand electrode (e.g., elasticity, plasticity, orother physical properties) may enable the strand electrode to bend orother accommodate contours of the skin surface while the distal endremains in physical contact with the skin surface. The strand electrodeis configured to enable ionic conduction at least at the point ofcontact. For example, the strand electrode may be made of, covered by(e.g., coated with, e.g., due to hydrophilicity of the strandelectrode), or filled with (e.g., absorb or have a hollow core filledwith) an ionically conducting material. Alternatively or in addition,the distal end of a strand electrode, or of a group of neighboringstrand electrodes, may terminate in an ionically conducting pad or tip.Alternatively or in addition, strand electrodes and the separationdistance between the strand electrodes may be configured to hold anionically conducting substance by capillary forces or otherwise (e.g.,hydrophilicity).

A proximal end of each strand electrode may be connected to an electrodebase. The electrode base may be connected to an external device. Theexternal device may include a signal generator or other source of anelectrical signal that is to be applied to the skin surface or a sensoror detector that is configured to sense or detect as signal that isproduced by the body. An electrical signal may thus be conducted by eachstrand electrode between the external device and the skin surface.

For example, one or more brush electrodes may be configured tofacilitate transcranial electric brain stimulation, such as,transcranial direct current stimulation (tDCS), random noise stimulation(RNS), transcranial alternating current stimulation (tACS), or othertranscranial stimulation. As another example, one more brush electrodesmay be configured to be used in EEG for sensing neural activity of thebrain. In some cases, the brush electrodes may be configured to transmitelectric stimulation signals at some times and to sense electric signalsat other times, or to concurrently transmit and sense, e.g., usingdifferent frequencies or frequency ranges.

A brush electrode as described herein may be advantageous over othertypes of electrodes. For example, other types of electrodes may requirespreading a conductive substance, e.g., in the form of a conductiveelectrolyte solution or gel, over an entire area of the electrode, orover an equivalent area of the skin. Thus, extensive cleanup of theskin, and any hair covering the skin, may be required after use of theelectrode. In particular, when the electrode is to be used on a hairyregion of skin, such as the head, attaining contact between theelectrode and the skin may require shaving that region of the skin. Inaddition, moving such an electrode about on the skin surface may wet theskin with the conductive substance and effectively increase the area ofcontact between the electrode and the skin, e.g., reducing precision ofa measurement or application of the electric signal.

A brush electrode as described herein in may be used on hair-coveredregions without shaving the hair. The distal ends of each electrodestrand may reach the skin between hairs. A conductive substance may beheld on the strand electrodes, e.g., by capillary forces in the narrowspace between adjacent strand electrodes, capillary forces within (e.g.,within a hollow core or between braids of) a strand electrode,absorption within a strand electrode, adsorption to the surface of thestrand electrode (e.g., by hydrophilicity of the strand electrode), orotherwise. Thus, it may not be necessary to spread the conductivesubstance over the skin. Thus, wetting of the skin may be reduced incomparison with use of other types of electrodes.

Some or all of the strand electrodes may be conducting, e.g.,constructed of a conductive polymer, metal, or other conductivematerial, or coated with a conducting material. In some cases, thedistal end of a strand electrode may be configured to penetrate into theskin, e.g., e.g., a stratum corneum layer, to facilitate electricalconduction between the body and the external device.

A thickness of each strand electrode may be selected for a particularapplication or type of application. Increasing the thickness of a strandelectrode may increase its rigidity. Such increased rigidity may beadvantageous where the strand electrode is to be used to penetrate hair,clothing, bandaging, skin, or in other situations where increasedrigidity may be advantageous. On the other hand, decreasing thethickness of a strand electrode may increase its flexibility. Increasedflexibility may enable the strand electrode to bend in order to increaseits area of contact with smooth skin, or may enable accommodatingvarious protrusions, depressions, or openings on the skin surface.

Similarly, a size of a cluster of strand electrodes, a number of strandelectrodes in each cluster, or selection of a structure or technique forholding a plurality of adjacent strand electrodes in the form of acluster, may be configured for a particular application or type ofapplication.

FIG. 1 schematically illustrates a cross section of a brush electrode,in accordance with an embodiment of the present invention.

Brush electrode 10 includes a plurality of strand electrodes 12.Although the cross sectional view of FIG. 1 shows a uniform linear arrayof strand electrodes 12 for convenience, it should be understood thatstrand electrodes 12 of a typical brush electrode 10 may be arranged ina two dimensional pattern (e.g., rectangular, circular, polygonal, oval,or other two-dimensional arrangement). A pattern of strand electrodes 12may include rows, circles, or other arrangements. Strand electrodes 12may be irregularly or non-uniformly distributed on brush electrode 10.

A distal end of each strand electrode 12 is configured to he placedagainst a skin surface 11.

Strand electrodes 12 may be configured to adhere to, to absorb, toadsorb, or to otherwise hold a conductive substance, e.g., in the formof an electrolyte solution for conducting ion charges through theelectrolyte solution to skin surface 11. In some cases, each strandelectrode 12 may be at least partially electrically conductive. Strandelectrodes 12 may be configured to facilitate an electrolysis interfacewith the conductive substance.

Brush electrode 10 includes electrode casing 15. For example, electrodecasing 15 may be configured to isolate all parts of strand electrodes12, e.g., except for exposed distal ends of strand electrodes 12, fromcontact with any other objects. Electrode casing 15 may be configured topartially or fully isolate strand electrodes 12 e.g., except for exposeddistal ends of strand electrodes 12, as well as other internalcomponents of brush electrode 10 from contact with an ambientatmosphere. Thus, electrode casing 15 may function to prevent contactwith external objects or with components of the atmosphere (e.g.,moisture, suspended particles, or other components of the ambientatmosphere) from interfering with operation of brush electrode 10.

Dimensions of electrode casing 15 may range from having a length of upto 5 mm, a width of up to 5 mm, and a thickness of up to 1 mm, to havinga length of up to 100 mm, a width of up to 100 mm, and a thickness of upto 40 mm (or other ratios between length, width and thickness).

Strand electrodes 12 of brush electrode 10 may he held in place, e.g.,in a particular arrangement, by electrode base 16. Electrode base 16 maybe incorporated into, or attachable to, electrode casing 15. Forexample, electrode base 16 may include an arrangement of openingsthrough which each strand electrode 12 may extend distally. In somecases, electrode base 16 may be configured to hold clusters of strandelectrodes 12 in a particular arrangement of clusters.

Electrode base 16 may be elastic, rigid, or pliable. In some cases,electrode base 16 may be electrically conductive, for example, made ofaluminum or another metal, conductive plastic or silicone, or anotherconductive material. In some cases, electrode base 16 may be made of anonconductive plastic, silicone, or other nonconductive material. Insome cases, electrode base 16 may be made of a combination of one ormore materials, including, but not limited to, materials mentionedabove. Electrode base 6 may be circular, rectangular, or otherwiseshaped, with a surface area in the range of about 1 square centimeter toabout 40 square centimeters. For example, a size and shape of electrodebase 16, or of brush electrode 10, may be selected to approximatelymatch (e.g., such that strand electrodes 12 cover) a target region ofthe skin surface to which brush electrode 10 is to be applied.

In the example shown, all strand electrodes 12 extended distally outwardin a direction that is substantially perpendicular to electrode base 16.In other examples, some or all of strand electrodes 12 may extenddistally outward from electrode base 16 at an oblique angle to electrodebase 16.

In some cases, each strand electrode 12 may extend distally outward fromelectrode base 16 by a distance that is no longer than 3 cm. In somecases, each strand electrode 12 may extend outward from electrode base16 by less than 2 cm, e.g., between 1 cm and 2 cm.

Strand electrodes 12 may be flexible, elastic, or plastic, e.g.,depending on a material from which each strand electrode 12 isconstructed, and on a lateral thickness of each strand electrode 12. Forexample, strand electrode 12 may be constructed of, or may include,conductive or nonconductive PA 6 nylon, PA 6.6 nylon, PA 6,10 nylon, PA6,12 nylon, or viscose. A strand electrode 12 may be made of Thunderon™,silicone, polyethylene or other polymer, elastomer, metal, agavebristle, animal hair, or other materials. In some cases, strandelectrodes 12 may be coated with a conductive material. In some cases,strand electrode 12 is not conductive but is coated with a conductivematerial.

A lateral thickness (e.g., diameter or other representative distancefrom one side of a strand electrode 12 to another) may range from 0.01mm to 1 min, e.g., in a range of lateral thickness from about 0.05 mm toabout 0.8 mm, or, more particularly, from about 0.15 mm to about 0.6 mm.A strand electrode 12 may have another lateral thickness.

A density of an arrangement of strand electrodes 12, e.g., on a surfaceof electrode base 16, may range from about 20 strand electrodes 12 persquare centimeter of surface area to about 200 strand electrodes 12 persquare centimeter of surface area. In some cases, the density may beselected in accordance with lateral thickness of each strand electrode12.

Strand electrodes 12 may be made of a material with a volume resistivityranging from about 10⁸ Ω-cm to less than 10³ Ω-cm. Similarly, surfaceresistivity may range from about 10⁸ Ω/square to less than 10³ Ω/square.

According to some embodiments, strand electrode 12 made of differentmaterials, or otherwise having different properties or characteristics,may be included in a single brush electrode 10.

Each strand electrode 12 may be electrically connected to an externaldevice. For example, the external device may be configured to generatean electrical signal, to receive an electrical signal, or both. Theexternal device may be wearable or other portable device, or may be anon-portable, e.g., desktop or other fixed, device. The external devicemay be battery powered, may be connected to a computer or computingcircuitry, or may be otherwise powered.

A proximal end of each strand electrode 12 of brush electrode 10 may beheld, e.g., by electrode base 16, in electrical contact with electrodeconductor 14. Typically, e.g., when single electrical signal is to beapplied concurrently to all strand electrodes 12, or when all strandelectrodes 12 are to conduct a single electrical signal from a skinsurface 11 to the external device, all strand electrodes 12 may beconnected to a single common electrode conductor 14. For example,electrode conductor 14 may be in the form of one or more plates or barsthat are constructed of a conducting metal, polymer, or other conductingmaterial. The plates or bars of electrode conductor 14 may be inelectrical contact with one another, e.g., directly or via a commonconductor to which all of the plates or bars are electrically connected.In some cases, e.g., where different strand electrodes 12 are configuredto carry concurrently different electrical signals, electrode conductor14 may include two or more conducting plates or bars that are notelectrically connected to one another.

For example, electrode conductor 14 may be connected via internalconductor 17 (e.g., that includes one or more conducting wires, cables,or bars) to external connector 18. For example, in some cases (e.g.,where brush electrode 10 is configured to function in place of atraditional ECG or EEG electrode) external connector 18 may include asimple male snap connector. In other cases, external connector 18 mayinclude another type of connector.

External connector 18 may be connected to an external device by a deviceconnector 20, e.g., that is connected to the external device by deviceconnection 22. For example, where external connector 18 is in the formof a male snap connector, device connector 20 may be in the form of afemale snap connector. is other examples, device connector 20 mayrepresent another type of connector. In some cases, device connector 20may include electrical or electronic circuitry. Device connection 22 mayinclude an electrical cable, or another type of wired or wirelessconnection to the external device.

In some cases, strand electrodes 12 may be arranged on electrode base 16in clusters of densely packed strand electrodes 12, with neighboringclusters being separated by gaps with no strand electrodes. Thearrangement in clusters may facilitate holding of a conductivesubstance, e.g., by capillary forces between the surfaces of differentstrand electrodes 12 in a cluster. The facilitated holding of theconductive substance may increase or facilitate conductivity betweenstrand electrodes 12 and a skin surface 11.

FIG. 2 schematically illustrates a cross section of a brush electrodehaving strand electrodes arranged in clusters in the form of tufts heldin place by staples.

In the example shown, strand electrodes 12 are arranged in clusters inthe form of electrode tufts 32. A plurality of strand electrodes 12 ineach electrode tuft 32 are connected to one another at their proximalends. For example, in some cases, the proximal ends of each strandelectrode 12 in an electrode tuft 32 may be formed by bending or foldinga single strand (e.g., that is approximately twice as long as eachstrand electrode 12) at proximal bend 35 to form two strand electrodes12. An electrode tuft 32 may be otherwise formed by a plurality ofstrand electrodes 12.

Each electrode tuft 32 may be held within electrode base 16 by tuftstaple 34. Tuft staple 34 may provide an electrical connection betweeneach strand electrode 12 of electrode tuft 32 and electrode conductor14. For example, tuft staple 34 may include a wire loop that surroundsboth proximal bend 35 and connects to electrode conductor 14 or anotherpart of electrode base 16 or of electrode casing 15. As another example,a tuft staple may be U-shaped, Such a U-shaped staple may be configuredsuch as the base of the U-shape holds proximal bend 35 of each electrodetuft 32 to (e.g., in electrical contact with) electrode base 16 when thearms of the U-shape are inserted into electrode base 16.

Each pair of neighboring electrode tufts 32 is separated by a clustergap 28.

FIG. 3 schematically illustrates a cross section of a brush electrodehaving clusters of strand electrodes that are held in place by ferrules.

Each electrode ferrule 36 is configured to hold in place withinelectrode base 16 the proximal ends of a plurality of strand electrodes12 of an electrode cluster 30. For example, at least an interior part ofelectrode ferrule 36 may be electrically conducting. Each electrodeferrule 36 may be connected via ferrule connector 38 to electrodeconductor 14, or otherwise to an external device. Thus, electrodeferrule 36 may connect strand electrodes 12 in each electrode cluster 30(e.g., via internal conductor 17 and external connector 18) to theexternal device. Each pair of neighboring electrode clusters 30 isseparated by a cluster gap 28.

For example, the number of strand electrodes 12 in each electrodecluster 30 may range from 5 strand electrodes 12 to more than 20. Thelateral thickness of each electrode cluster 30 may be circular or oval,ranging from about 0.5 mm to about 4 mm, and may have a cross-sectionarea of in the range of about 1 square millimeter to about 40 squaremillimeters. The length of an electrode cluster 30 may range from about5 mm to about 20 mm.

A density of a distribution of electrode clusters 30, e.g., on a distalsurface of electrode base 16, may range from less than 2 electrodeclusters 30 per square centimeter to 100 electrode clusters 30 persquare centimeter. A representative length of cluster gap 28 (e.g., aminimum distance between adjacent electrode clusters 30) may range fromabout 0.5 mm to about 8 mm.

When all strand electrodes 12 in an electrode cluster 30 are of equallength and extend perpendicularly distally outward from electrode base16, then a distal face of electrode cluster 30 may be substantiallyflat. In some cases, different strand electrodes 12 of a singleelectrode cluster 30 may have different lengths. In such a case, adistal face 33 of electrode cluster 30 may be substantially flat,perpendicular to strand electrodes 12, and parallel to electrode base16. In other cases, strand electrodes 12 of different lengths may bearranged to form a distal face that is planar but tilted, convex, orotherwise shaped. A single electrode cluster 30 may include strandelectrodes 12 of different materials and dimensions.

A brush electrode 10 may be configured to hold a conductive substance.For example, the conductive substance may be applied by a user of brushelectrode 10, e.g., by dipping strand electrodes 12, or an electrodecluster 30, into a conductive substance in the form of a liquid or gel(e.g., an electrolyte solution or other conductive substance in the formof liquid or gel). As another example, a brush electrode 10 may beprovided by a producer or vendor of brush electrode 10 with a conductivesubstance already applied to strand electrodes 12 or to electrodeclusters 30 (e.g., within a sealed container, envelope, or packaging.

FIG. 4 schematically illustrates a cross section of brush electrode asshown in FIG. 3 , with an electrolyte solution adhering to the clustersof conductive strand electrodes.

As used herein, a strand electrode, or a part of a strand electrode, isconsidered to be conductive when constructed of an electronicallyconductive material that is configured to conduct electrical current inthe form of electrons (e.g., such as a metal or other electronicallyconductive substance).

Each electrode cluster 30 is shown as holding conductive substance 40among electronically conductive strand electrodes 31. For example,conductive substance 40 may be held within electrode cluster 30 bycapillary forces among electronically conductive strand electrodes 31.

In the example shown, electronically conductive strand electrodes 31 maybe assumed to be conductive so as to facilitate electrolysis, e.g.,within conductive substance 40.

Other types of electrodes, or combinations of different types ofelectrodes, may be included in a brush electrode 10 whose strandelectrodes are configured to hold a conductive substance 40.

In an example of a brush electrode 10, an electrode cluster 30 includesapproximately 40 strand electrodes (e.g., electrically conductive orotherwise), each about 1.2 mm long with a diameter of about 0.3 mm. Insome examples, the strand electrodes may be made of or may includeconductive nylon PA6.

The structure of electrode cluster 30 is such that a liquid electrolytemay he held between the strand electrodes by physical or chemicalproperties of the electrolyte, properties of the surfaces of the strandelectrodes, structural properties of electrode cluster 30 (e.g., densityor another property of the distribution of the strand electrodes), or acombination of these properties. For example, the strand electrodes maybe elastic. Therefore, placing brush electrode 10 on a target region ofskin surface 11 may cause the strand electrodes to bend to accommodateany curvature or other topography of skin surface 11 while continuing tohold the electrolyte. The elasticity may enable the strand electrodes tomove together without separating from one another, so that at least someof the electrolyte remains held between neighboring strand electrodes tofacilitate electrolysis and ionic conduction of an ionic electricsignal.

In another example, the elasticity of the strand electrodes may besufficiently weak (e.g., weaker than physical forces, e.g., capillaryforces or surface tension, holding a liquid electrolyte betweenneighboring strand electrodes) such that a change in the position of oneor more strand electrodes, for example by bending, may affect one ormore neighboring or adjacent strand electrodes to change position in asimilar manner (e.g., by a force transmitted via an electrolyte or otherliquid held among the strand electrodes).

FIG. 5A schematically illustrates a variant of a cross section of abrush electrode as shown in FIG. 4 , with segmented strand electrodesthat are partially electrically conductive and partially nonconductive.FIG. 5B schematically illustrates a segmented strand electrode of thebrush electrode shown in FIG. 5A.

As used herein, a strand electrode, or part of a strand electrode, isreferred to as nonconductive when that strand electrode, or that part ofa strand electrode, does not conduct electrons. The nonconductive strandelectrode or part may be electrically insulating (e.g., as defined by alow electric conductivity), or may be configured to primarily conductelectricity by motion of ions. For example, a strand electrode may beionically conducting if constructed of an ionically conductive material,e.g., of an ion-conducting polymer such aspoly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) oranother ion-conducting polymer, or may be coated with a conductivesubstance 40 that is conductive of ions.

In the example shown, proximal segment 44 of each segmented strandelectrode 42 is electrically conductive. The electrically conductiveproximal segment 44 may facilitate electrolysis within conductivesubstance 40. Distal region 46 of each segmented strand electrode 42 iselectrically nonconductive. Electrically nonconductive distal region 46may provide a medium to enable conductive substance 40 and ionic chargesto reach a skin surface 11 against which distal regions 46 are placed incontact.

FIG. 6 schematically illustrates a variant of a cross section of a brushelectrode as shown in FIG. 4 , where each electrode cluster includesdifferent types of strand electrodes.

In the example shown, each electrode cluster 30 includes both conductiveelectronically conductive strand electrodes 31, and nonconductive strandelectrodes 48. For example, conductive electronically conductive strandelectrodes 31 may facilitate electrolysis, e.g., in conductive substance40. Nonconductive strand electrodes 48 may function as a medium toenable conductive substance 40 to reach skin surface 11. Nonconductivestrand electrodes 48 may be electrically insulating or may be ionconducting.

In other examples, different types of strand electrodes may havedifferent mechanical characteristics, electrical characteristics,chemical characteristics, or may differ with regard to other types ofcharacteristics.

FIG. 7 schematically illustrates a variant of a cross section of a brushelectrode as shown in FIG. 4 , where electrolysis is configured to occurat a proximal end of each strand electrode.

In the example shown, conductive substance 40 is present withinelectrode base 16. For example, conductive substance 40 may be presentwithin each electrode ferrule 36, as shown, or elsewhere withinelectrode base 16.

In this case may be configured to conduct the ions from electrode base16 to a skin surface 11 with which the distal ends of the strandelectrodes are in contact. In the example shown, strand electrodes inthe form of nonconductive strand electrodes 48 are coated withconductive substance 40. Alternatively or in addition, nonconductivestrand electrodes 48 may he ionically conductive (e.g., withoutconductive substance 40), or the strand electrodes may includeelectronically conductive strand electrodes 31 that are coated withconductive substance 40.

FIG. 8 schematically illustrates an example of a cross section of abrush electrode that includes an electrolyte reservoir within theelectrode casing.

In the example shown, electrode conductor 14 in connected to a pluralityof electrolysis electrodes 52. Each electrolysis electrode is configuredto be at least partially immersed in an electrolyte within electrolytereservoir 50.

In the example shown, electrolyte reservoir 50 is enclosed in electrodecasing 15 outside of electrode base 16. Alternatively or in addition,electrolyte reservoir 50 may be located within electrode base 16.Electrolysis may occur within electrolyte reservoir 50, e.g., atelectrolysis electrodes 52. The strand electrodes may includenonconductive strand electrodes 48, e.g., that are ionically conducting.Alternatively or in addition, the strand electrodes may includeelectronically conductive strand electrodes 31 or resistivenonconductive strand electrodes 48 that covered by a conductivesubstance 40.

In some cases, strand electrodes or electrode clusters of a brushelectrode 10 may he configured to facilitate contact of the distal endsof the strand electrodes with a skin surface 11.

FIG. 9 schematically illustrates a variant of the cross section of abrush electrode shown in FIG. 3 , with strand electrodes havingdifferent lengths.

In the example shown outer electrode clusters 54 a are located near alateral edge of brush electrode 10, while inner electrode clusters 54 bare located interior to (e.g., further away from an edge than) outerelectrode clusters 54 a. In the example shown, strand electrodes 56 a ofouter electrode clusters 54 a are longer than strand electrodes 56 b ofinner electrode clusters 54 b. This configuration may facilitate contactof the distal ends of strand electrodes 56 a and 56 b with a convex skinsurface 11 (e.g., a head, limb, or other convex surface).

In other examples, inner strand electrodes 56 b may be longer than outerstrand electrodes 56 a, e.g., to facilitate contact with a concave skinsurface 11.

Typically, a brush electrode 10 may include more than four electrodeclusters (e.g., more than in the example shown). In such a case, thelengths of the strand electrodes in the electrode clusters may graduallyincrease or decrease with increasing distance from a center of thatbrush electrode 10.

FIG. 10 schematically illustrates a variant of the cross section of abrush electrode shown in FIG. 3 , having a curved electrode base.

In the example shown, all strand electrodes 12 have the same length.However, curved electrode base 60 is concave (e.g., as viewed from thedirection of a skin surface 11). Such a concave curved electrode base 60may facilitate contact of the distal ends of strand electrodes 12 (e.g.,where all strand electrodes 12 extend distally by equal lengths from aconnection of each strand electrode 12 with concave curved electrodebase 60) with a convex skin surface 11 (e.g., on a head, limb, or otherconvex surface).

In other examples, curved electrode base 60 may be convex, e.g., tofacilitate contact of the distal ends of strand electrodes 12 with aconcave skin surface 11 (e.g., at an inner joint in a limb or in theneck region).

In some cases, a brush electrode 10 ay include both electrode clustersof different lengths and a curved electrode base 60.

FIG. 11 schematically illustrates a variant of the cross section of abrush electrode shown in FIG. 3 , having tilted strand electrodes.

Strand electrodes 12 of each tilted electrode cluster 62 extend distallyoutward at an oblique angle to (e.g., the distal face of) electrode base16. For example, the tilt of each tilted electrode cluster 62 mayfacilitate penetration of hair to an underlying skin surface 11, or mayincrease comfort of a subject whose skin is contacted by strandelectrodes 12.

FIG. 12 schematically illustrates a variant of the cross section of abrush electrode shown in FIG. 11 , having strand electrodes that aretilted laterally outward.

In the example shown, strand electrodes 12 of each outwardly tiltedelectrode cluster 64 are tilted laterally outward (e.g., such that theirdistal end of each strand electrode 12 is further from a center of brushelectrode 10 than its proximal end), each at an oblique angle to (e.g.,the distal face of) electrode base 16. The laterally outward tilt may,in addition to facilitating hair penetration and promoting comfort, maycontribute to stability of placement of brush electrode 10 on a skinsurface 11. For example, the outward lateral tilt may impede lateralsliding of brush electrode 10 across skin surface 11.

In other examples, outwardly tilted electrode cluster 64 may have otherorientations. For example, in addition to a laterally outward tilt, eachoutwardly tilted electrode cluster 64 may also have an azimuthal tilt orslant. The azimuthal slant may, in some cases, enable placement of brushelectrode 10 a skin surface 11 with a lateral twisting motion. Such anazimuthal slant may further facilitate hair penetration and contact ofstrand electrodes 12 with a skin surface 11.

In some cases, different parts of a brush electrode 10 may be configuredto apply or sense different electrical signals, or to facilitateplacement of different brush electrodes 10 in close proximity to oneanother, e.g., to facilitate application or sensing of differentelectrical signals.

FIG. 13 schematically illustrates a variant of the cross section of abrush electrode shown in FIG. 3 , configured to separately connect eachelectrode cluster to an external device.

In the example shown, each electrode cluster 30 is connected to aseparate external connector 58 via a separate internal conductor 57.Each external connector 58 may be separately connected to a differentexternal device, or to a different port or connector of the externaldevice. Thus, a different electrical signal may be separately applied toeach electrode cluster 30, or may be separately sensed via eachelectrode cluster 30. For example, in some cases, an electrical signalmay be applied to one or more electrode clusters 30, while an electricalsignal may be concurrently sensed by one or more other electrodeclusters 30.

In other examples, groups of two or more electrode clusters 30 (e.g.,neighboring electrode clusters 30) may be connected to differentexternal connectors 58.

FIG. 14 schematically illustrates a variant of the cross section of abrush electrode shown in FIG. 3 , with isolating barriers.

Isolating barriers 68 may be electrically insulating. Isolating barriers68 may enable placement of two brush electrodes 10 in close proximity toone another. In this case, isolating barriers 68 may prevent contactbetween strand electrodes 12 or conductive substances 40 of adjacentbrush electrodes 10. Isolating barriers 10 may include a hydrophobicmaterial to inhibit passage or water or of water-based substances, ormay be water absorptive to absorbing any electrolyte that may otherwiseseep between isolating harriers 68 and skin surface 11.

FIG. 15 schematically illustrates a variant of the cross section of abrush electrode shown in FIG. 13 , having isolating barriers betweenelectrode clusters.

Isolating barriers 68 may prevent contact between strand electrodes 12of neighboring electrode clusters 30. This may be advantageousespecially when a different electrical signal is applied to, or issensed by, each electrode cluster 30.

In some cases, electrical ionic contact between strand electrodes 12 anda skin surface 11 may be facilitated by connecting the distal ends ofgroups of one or more strand electrodes 12 to an ionically conductingtip.

FIG. 16 schematically illustrates a variant of the cross section of abrush electrode shown in FIG. 3 , where the distal ends of groups ofstrand electrodes within a single electrode cluster terminate in anion-conducting tip.

In the example shown, each group of neighboring strand electrodes 12within an electrode cluster 30 terminates in a single ion-conducting tip70. For example, strand electrodes 12 may be electronically conductiveand ion-conducting tip 70 may be made of an ionically conductivematerial.

FIG. 17 schematically a variant of the cross section of a brushelectrode shown in FIG. 3 , where all strand electrodes in an electrodecluster terminate in a single ion-conducting tip.

Distal ends of all strand electrodes 12 in a single electrode cluster 30terminate in a single ion-conducting cluster tip 71.

FIG. 18 schematically illustrates variants of electrode clusters of thecross section of a brush electrode shown in FIG. 17 .

For example, interwoven electrode cluster 72 may include strandelectrodes 12 that are braided, twisted together, or otherwiseinterwoven or interlocked.

In electrode cluster 30 a, distal segments of strand electrodes 12 arecovered by partial sleeve 74. Partial sleeve 74 may enable wetting ofthe distal segments with an electrolyte without wetting skin surface 11.The electrolyte may be introduced at a proximal end of partial sleeve74. For example, partial sleeve 74 may be constructed of silicone,nylon, or another material that is flexible and impermeable to anelectrolyte.

In electrode cluster 30 b, strand electrodes 12 are completely coveredby full sleeve 76. Full sleeve 76 may enable wetting of the entirelengths of strand electrodes 12 without wetting skin surface 11. Theelectrolyte may be introduced into full sleeve 76, e.g., from withinelectrode base 16 or elsewhere within electrode casing 15. For example,full sleeve 76 may he constructed of silicone, nylon, or anothermaterial that is flexible and impermeable to an electrolyte.

Strand electrodes may have various forms, e.g., in addition to those ofelectronically conductive strand electrode 31, segmented strandelectrode 42, and nonconductive strand electrode 48, described above.

FIG. 19 schematically illustrates variants in the forms of longitudinalcross sections strand electrodes for a brush electrode as shown in FIG.1 .

Porous strand electrode 80 may be constructed of a porous material,e.g., to facilitate adherence of a conductive substance 40. Braidedstrand electrode 82 may be constructed of a plurality of braided orinterwoven thin strands, e.g., to enable absorption of an electrolyte. Adiameter or other lateral dimension of non-uniform profile strandelectrode 84 may vary along its length, either monotonically, as in theexample shown, or otherwise. Tipped strand electrode 86 may include anion-conducting electrode tip 88.

Strand electrodes may be constructed with different transversecross-sectional shapes.

FIG. 20 schematically illustrates variants of a transversecross-sectional shape of a strand electrode for a brush electrode asshown in FIG. 1 .

Cross sectional shapes may include, for example, solid circular 90,porous circular 92 (e.g., to enable absorption of an electrolyte),serrated 94 (e.g., to facilitate adsorption of an electrolyte), hollowcircular 96 (e.g., to enable holding an electrolyte within the strandelectrode), trefoil 98, triangular 100 (or other regular polygonal),cross-shaped 102 (or other irregular polygonal), or other shapes (e.g.,oval, hollow, porous, or solid variants, or other shapes, such as ovalsor other shapes).

Selection of a form of a strand electrode may be determined, at least inpart, by various electrical, chemical, or mechanical properties for aparticular application.

Although electrode base 16 has been shown in cross section in FIGS. 1-18, electrode base 16 typically extends in two lateral dimensions (e.g.,length and width, in addition to its thickness or height).

FIG. 21 schematically illustrates a face of an electrode base of a brushelectrode as shown in cross section in FIG. 3 .

Electrode base face plate 104 is configured to cover a distal face ofelectrode base 16 (e.g., a face that faces skin surface 11 when in use).Each electrode cluster opening 106 is configured to enable an electrodecluster 30 to extend distally outward through electrode base face plate104. Spaces between electrode cluster openings 106 may determine thesizes of cluster gaps 28.

Although in the example shown, electrode cluster openings 106 arearranged in a rectangular array, other arrangements are possible. Thearrangement and distribution (e.g., diameter or other lateral size,spacing between, or other characteristics of the arrangement ordistribution) of electrode cluster openings 106 may be selected asappropriate to a particular application of a brush electrode 10.

FIG. 22 schematically illustrates a system that includes a plurality ofbrush electrodes, in accordance with an embodiment of the presentinvention.

Brush electrode system 110 includes an external device 112 that isconnected to a plurality of brush electrodes 10.

External device 112 may include one or more devices. For example, adevice of external device 112 may be configured to generate one or moreelectrical signals that may be applied to skin surface 11 via brushelectrodes 10. A device of external device 112 may be configured tosense an electrical signal (e.g., an EEG signal or other signal) that isgenerated within a body and that may be detected by a brush electrode 10in contact with skin surface 11.

Each brush electrode 10 may be configured to enable identification byexternal device 112. For example, an identification mechanism mayinclude application of Inter-Integrated Circuit (I²C) technology, or mayinclude providing each brush electrode 10 with a unique impedancefootprint that is identifiable by external device 112. Theidentification mechanism or a database that is accessible by a processorof external device 112 may enable identification of one or more featuresor characteristics of each brush electrode 10. Such features andcharacteristics may include, for example, contact area, configuration ofstrand electrodes 12, or other features or characteristics.

For example, external device 112 may be connected by one or more deviceconnections 22 to one or more device connectors 20. Each deviceconnector 20 may be connected to a separate brush electrode 10.

FIG. 23 schematically illustrates a brush electrode with hollow strandelectrodes, in accordance with an embodiment of the present invention.

In brush electrode 120, hollow strand electrodes 122 are organized inclusters 128. Control circuitry 132 may be electrically connected toeach cluster 128 by cluster conductor 134.

Each hollow strand electrode 122 has a hollow core and is coated withinsulating coating 124. Insulating coating 124 may prevent electricalcontact between adjacent hollow strand electrodes 122. A distal end ofeach hollow strand electrode 122 terminates in an ion-conducting tip126.

An electrolyte may he introduced into electrode casing 15 viaelectrolyte orifice 130. For example, electrolyte orifice 130 may beconfigured to enable electrolyte to flow into electrode casing 15, andto impede or prevent outflow of electrolyte from electrode casing 15.

The electrolyte may flow from electrode casing 15 into the hollow coreof each hollow strand electrode 122. Thus, electrolysis may occur withineach hollow strand electrode 122. The ionic current may be conducted viaion-conducting tip 126 into a skin surface with which ion-conducting tip126 is in contact.

Different embodiments are disclosed herein. Features of certainembodiments may be combined with features of other embodiments; thuscertain embodiments may be combinations of features of multipleembodiments. The foregoing description of the embodiments of theinvention has been presented for the purposes of illustration anddescription. It is not intended to be exhaustive or to limit theinvention to the precise form disclosed. It should be appreciated bypersons skilled in the art that many modifications, variations,substitutions, changes, and equivalents are possible in light of theabove teaching. It is, therefore, to be understood that the appendedclaims are intended to cover all such modifications and changes as fallwithin the true spirit of the invention.

While certain features of the invention have been illustrated anddescribed herein, many modifications, substitutions, changes, andequivalents will now occur to those of ordinary skill in the art. It is,therefore, to be understood that the appended claims are intended tocover all such modifications and changes as fall within the true spiritof the invention.

1. A brush electrode comprising: an electrode base that is connectableto an external device that s configured to generate an electrical signalor receive an electrical signal; and a plurality of strand electrodesthat extend outward from the electrode base, a distal end of each strandelectrode configured to contact a skin surface, said plurality of strandelectrodes configured to facilitate conduction of the electrical signalto or from the skin surface, wherein the strand electrodes are clusteredinto a plurality of clusters of strand electrodes, neighboring clustersof said plurality of clusters being separated from one another by gapswithout any strand electrodes, and wherein different dusters comprisestrand electrodes of different lengths.
 2. The brush electrode of claim1, wherein the strand electrodes are configured to hold an electrolyteto facilitate ionic conduction.
 3. The brush electrode of claim 2,wherein a cluster of said plurality of clusters is held to the base by astaple or a ferrule.
 4. The brush electrode of claim 2 or 3, whereinsaid plurality of clusters are electrically connected to a singleexternal connector for connecting to the external device.
 5. The brushelectrode of any of claim 2 or 3, wherein at least two clusters of saidplurality of clusters are connected to different external connectors forconnecting separately to the external device.
 6. The brush electrode ofany of claims 1 to 5, further comprising an isolating barrier forelectorally isolating two clusters of said plurality of clusters fromone another.
 7. The brush electrode of any of claims 2 to 6, whereinsaid plurality of strand electrodes are configured to hold theelectrolyte by capillary forces.
 8. The brush electrode of any of claims2 to 7, wherein a strand electrode of said plurality of strandelectrodes includes a hollow core that is configured to be filled withthe electrolyte, or is configured to absorb or adsorb the electrolyte.9. The brush electrode of any of claims 1 to 8, wherein a strandelectrode of said plurality of strand electrodes is electricallyresistive or ionically conducting.
 10. The brush electrode of any ofclaims 1 to 9, wherein a proximal segment of a strand electrode of saidplurality of strand electrodes is electronically conducting, and adistal segment of that strand electrode is electrically resistive orionically conducting.
 11. The brush electrode of any of claims 1 to 10,further comprising an electrolyte reservoir.
 12. The brush electrode ofany of claims 1 to 11, wherein the electrode base is curved.
 13. Thebrush electrode of any of claims 1 to 12, wherein the strand electrodesextend outward from the electrode base at an oblique angle to theelectrode base.
 15. The brush electrode of claim 14, wherein the strandelectrodes are tilted laterally outward.